What is dizziness during pregnancy?

Dizziness is when you feel lightheaded or you feel like you are about to faint. You feel like you're spinning or things around you are spinning (vertigo).

What is syncope or fainting during pregnancy?

Syncope or fainting is a temporary loss of consciousness. It is often related to insufficient blood flow to the brain. It's also called fainting or "passing out." It most often occurs when blood pressure is too low (hypotension) and the heart doesn't pump enough oxygen to the brain.

The most common cause of syncope in women of childbearing age is vasovagal syncope.

What is a vasovagal syncope?

A vasovagal syncope is sudden fainting. It is usually caused by a sudden drop in heart rate and blood pressure when your body changes positions such as when you suddenly get up from sitting or lying down. It can also happen when your body overreacts to certain emotional or neurologic triggers.

If you experience a vasovagal syncope, you may also experience certain skin, vision, circulatory, and other associated symptoms such as pale skin or the sensation of breaking out in a cold sweat, dilated pupils, tunnel vision or blurred vision, a slow or weak pulse, lightheadedness, frequent yawning, headache, nausea, and feeling hot or overheated with no clear cause.

A vasovagal syncope in and by itself is usually not harmful or indicative of a more serious condition but you should talk to your doctor when it happens.

Can dizziness or fainting and syncope be a problem during pregnancy?

There are several potential problems associated with dizziness of fainting and syncope. 

Fainting is a symptom that can be due to several causes, ranging from not seriouis to more serious issues. If you faint, it's important to determine the cause of syncope and any underlying conditions.

The following conditions can trigger fainting or syncope:

• Dehydration
• Heavy sweating
• Exhaustion
• The pooling of blood in the legs due to sudden changes in body position
• Serious heart conditions, such as bradycardia, tachycardia or blood flow obstruction 

Certain medical conditions may be accociated with dizziness. In these cases it usually goes away after you're treated. For example:

• dehydration or heat exhaustion
• an ear infection
• migraine
• stress or anxiety
• low blood sugar level (hypoglycemia)
• iron deficiency anemia
• motion sickness

What to do when you experience dizziness or fainting during pregnancy

If you experience the warning signs of fainting of dizziness,  you should sit or lie down, maybe with your feet elevated. If you have syncope or you faint, you should receive an initial evaluation, including detailed physical and history examinations and measurement of blood pressure and heart rate, by a physician. An ECG (electrocardiogram) is also recommended as part of an initial evaluation to provide information about the cause of syncope. Other tests in cluding certain blood tests or exercise stress test, Holter monitor and an echocardiogram, may be needed to rule out other cardiac causes.

Increased pregnancy complications are associated with syncope and fainting during pregnancy

A study published in 2019 in the Journal of the American Heart Association found that pregnant women who experienced syncope had a higher rate of preterm birth and a higher incidence of congenital anomalies, with the highest rates of these adverse events among women who had an episode of syncope in the first trimester.

Moreover, women with an episode of syncope also had higher rates of cardiac arrhythmias and syncope episodes within a year after pregnancy versus women with no syncope.

The authors recommended that "given the observed higher rates of adverse outcomes among women experiencing syncope in pregnancy, closer monitoring both during pregnancy and in the postpartum period may be necessitated."